There are growing concerns about the apparent relationship of increasing the concentration of greenhouse gases and the global warming phenomenon. As a consequence, a broad consensus has developed as to the need to reduce CO2 emissions associated with various human activities.
Carbon dioxide emissions (CO2) from hydrocarbon-fueled transportation vehicles powered by internal combustion engines (ICE) constitute a significant part of the total man-made greenhouse gas emissions. As a result, adoption of new rules to significantly reduce CO2 from vehicles are currently being considered in many countries around the world. As an example, action was recently taken by the State of California to adopt new regulations that require significant reductions in CO2 emissions from road vehicles by the year 2016.
Emissions of CO2 from stationary energy sources such as power plants can be efficiently separated and captured either ahead of, or after the combustion process using processes and apparatus known in the art. These techniques are impractical in the case of mobile vehicular systems such as automobiles, trucks and buses, principally due to the associated high cost and limited availability of on-board space. Current efforts to address the need to reduce CO2 emissions from mobile systems, such as transport vehicles, involve optimization of fuel economy through measures that include enhancing the efficiency of the combustion engine and the power train, adoption of more fuel-efficient power trains (e.g., hybrids), and the reduction of rolling and drag losses.
All of these steps taken together have resulted in a measurable reduction of CO2 emissions from automobiles. However, the extent of these reductions may not be sufficient to maintain an acceptable level of CO2 emissions in view of the rapidly growing automotive transportation sector. Because of these concerns, alternative propulsion systems using non-carbon or carbon-neutral fuels have been given serious consideration and it has been urged by some that they gradually replace current hydrocarbon-fueled ICE-based systems. These alternative systems, however, will require substantial alterations to the transportation fueling infrastructure that has been developed on a worldwide basis over the past century.
Various strategies have been proposed for reducing the production of CO2 entering the atmosphere to mitigate global warming. Decarbonization of fossil fuels has been identified with the process of removing carbon before or after combustion. Fossil Fuel Decarbonization Technology for Mitigating Global Warming, Brookhaven National Laboratory (1997-98).
It has been proposed that natural gas be subjected to thermal decomposition, or pyrolysis, in the absence of air for the production of (1) hydrogen as a clean-burning fuel or feed stream to fuel cells and (2) carbon black, which is a form of elemental carbon. Hydrogen from Natural Gas Without Release of CO2 to the Atmosphere, Int'l S. Hydrogen Energy, Vol. 23, No. 12, pp. 1087-1093 (1998). The thermal decomposition in this case is achieved by a plasma arc process that utilizes electricity to form the plasma using hydrogen.
A process for the thermocatalytic decomposition of hydrocarbons into hydrogen and elemental carbon in the absence of air has been disclosed. Thermocatalytic CO2-Free Production of Hydrogen from Hydrocarbon Fuels, N. Muradov, Proceedings of the 2002 U.S. DOE Hydrogen Program Review, NREL/CP-6 10-32405. The reaction is catalyzed by the carbon particles produced in the process.
A process for methane decomposition in the presence of a small amount of oxygen in an auto-thermal regime was disclosed by N. Muradov in a keynote paper presented at the 2nd European Hydrogen Energy Conference, Spain, November 2005. This process uses activated carbon as a catalyst for the decomposition reaction.